"Going to keep a diary?" Dave said on coalition night. "Cos I won't have time." We were driving back from the Queen. Oh sure, I said, you know how much I love writing. Course I'm fucking not. Then he said, "Absolutely sure?" and took this hideous object out of his briefcase and I didn't have much choice, given it was one of my own, signature Wag-dazzlers, the medium-size manuscript book in fuchsia lambskin, and he'd sweetly got it customised with Mrs Cameron's Diary in gold where it normally says "Luncheons, Suppers and Dinners". We couldn't talk any more, anyway, because his mobile went, and it was poor Cleggy wanting to know what the Queen was like. "Incredibly nervous," Dave said. "As you'd expect. But Sam soon put her at her ease."

Then we looked at the PM's flat, which is basically a two-floor caravannette with a filthy carpet and walls the colour of sick. Hilarious. We were still going oh my actual God and taking photographs of each other doing vomit faces when the phone went. "Very nice," Dave told Cleggsy. "Big. Loving the colours."

Since when Dave's been in London thinking what to cut, and I've been crying a lot in Ibiza, as any normal person would. I mean, a collapsing economy you can factor in. But who knew about Cherie's granite'n'pine kitchenette with wrought-iron handles, stained banquette seating and midget fridge? Plus the powder-blue carpets, louvred wardrobes, marble-topped commodes, nests of tables, pleated lampshades, lattice radiator-covers, glass-fronted bookshelves and floral pelmets? Got to hand it to the Blairs, I told Mummy, they knew how to make the average Bupa waiting room look like Versailles.

So well done me getting back from Ibiza with a complete plan for a simple yet stylish family home: waxed cement floors, neutral tones, colour from the odd accented wall, sofas and – nod at tradition – a few vintage pieces. Once you knock through No10 into 11, the sightlines go right through from the open-plan kitchen to a glass wall overlooking Horseguards. Couldn't wait to show Dave. "Surprise!" I said, when the kids were asleep. "Can it wait, babe?" he said, reaching for his BlackBerry. "That'll be Nick."